JPS6322950B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for correcting a grinding wheel in a grinding machine.

The shaping of the grinding wheel on a grinding machine and its correction are generally carried out by template hydraulic tracing, but when grinding, the shape of the finished product does not follow the exact shape of the template, and often there is a difference of several μm. The value differs depending on the machine, and there were cases where it was difficult to obtain the accuracy of the profiling step. Conventionally, such cases have been solved by correcting the template by the amount corresponding to the error, but this has had the disadvantage of requiring considerable time and expense. Also, change the step,
If you want to eliminate it, you need another template.Furthermore, there are restrictions on the angles of normal corrective scanning and reverse slope scanning, which is inconvenient.

Therefore, the present invention was made to solve the above-mentioned drawbacks, and it is possible to modify the grinding wheel so that the finished surface has the correct dimensions without modifying the template, and it is also possible to modify the grinding wheel to a shape different from that of the template. The first aspect of the present invention is to provide a method and a device that can be used for contouring using fluid pressure or electricity for tracing parts that require extremely delicate smoothness, such as tapered parts and crowning parts of workpieces. The control of the grinding wheel generatrix direction of the correction device is
This is a method in which NC is used to control the cutting and returning of a diamond tool of a correction device when it is desired to cut in or return a step or straight part, or to modify a shape that is not in the shape of a template. The second invention is an apparatus for carrying out the first invention, in which a copying shaft is provided with a copying device using fluid pressure or electricity, and the copying device is moved in the direction of the grindstone generatrix.
The present invention is characterized in that an NC axis is provided, an NC axis is provided for moving the cutting table in the cutting direction of the diamond tool, and a means for driving and controlling each NC axis is provided.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In explaining embodiments of the present invention with reference to FIGS. 1 and 2, a well-known correction device for an angle slide grinding machine will be described as an example. A grindstone head on a bed (not shown) is provided with a notch diagonally to the stepped workpiece supported between a headstock and a tailstock on the table, and a whetstone shaft is rotatably provided on the stepped workpiece. An angle grindstone 1 is attached to the tip of the grinding wheel. A grindstone correction device is provided on the back surface of the grindstone 1 on the opposite side from the workpiece. In this grinding wheel correction device, a cutting table 2 is placed on the grinding wheel table so as to be movable in the cutting direction (Y-axis) of the grinding wheel, and a ball screw 3 whose shaft end is fixedly supported is placed on the wheel table so that it can only rotate. It is threadedly engaged with the female thread of the worm wheel 4 which is supported thereon. This worm wheel 4 is rotated by a timing belt 6 from a feed motor 5 fixedly installed on the grinding wheel head, and meshes with a worm 9 supported on the grinding wheel head together with a pulley 8 having a dog 7 at a 180° position. Feed motor 5 by command from NC
By rotating the cutting table 2, cutting control of the cutting table 2 is performed. A tachometer generator 10 and a position detector 11 via gears are connected to the feed motor 5, and their respective outputs are sent to the NC device. The grindstone head is also provided with a limit switch 12 for detecting excessive depth of cut, which outputs a signal through the dog 7. Two dogs 13 are fixedly mounted on the sides of the cutting head 2 and act on a limit switch 14 on the grinding wheel head at the limit of travel. Furthermore, a traverse table 15 is integrally provided on the cutting table 2 and has a guide surface at an angle of 30 degrees to the grinding wheel shaft in this example in the generatrix direction of the angle grinding wheel 1.A ball screw 17 with a pulley 16 fixed to one end thereof is mounted on the cutting table 2. is restrained from moving in the axial direction and is supported by a shaft so that only rotation is possible. A copying saddle 18 is placed on the traverse table 15 so as to be able to slide on a guide surface in the 30° (W axis) direction with respect to the grinding wheel shaft. Rotation is transmitted from the feed motor 21 on the traverse table 15 via the timing belt 19 and pulley 20.
The copying saddle 18 is controlled to be fed by rotating the feed motor 21 in response to an NC command. Further, the feed motor 21 is connected to a tachometer generator 22 and a position detector 23 via gears, and the respective outputs are sent to the NC device. Two dogs 24 are fixedly attached to the copying saddle 18 at two positions in the traverse direction, and act on a limit switch 25 on the traverse table 15 at the two extreme positions. The copying saddle 18 has a ball guide 26 in the cutting direction of the cutting table 2.
The ram 27 is fitted without any gaps so that the ram 27 can slide accurately. This profiling ram 27 has a diamond tool 28 for dressing at the tip on the side of the grinding wheel 1, and a template 29 fixed precisely in the W-axis direction on the cutting table 2 at the bottom of the rear end so that its longitudinal position can be adjusted. Feeler to imitate 30
is provided. This copying ram 27 is connected to a fluid pressure cylinder 31 provided on the cutting table 2 in the cutting direction.
Piston rod 33 of piston 32 fitted in
The filler 30 is connected to the template 2.
9 with a predetermined pressure.

A dog 34 is protruded from the side surface of the copying ram 27 and operates a copying ram retreat end limit switch 35 on the copying saddle 18. The oil passages to the upper and lower chambers of the hydraulic cylinder 31 are switched and connected to the pressure source and discharge side, respectively, via two-position switching valves 36 and 38, and the pressure side is configured to compensate for pressure fluctuations. An accumulator 37 and a relief valve 39 for maintaining a constant pressure are provided. And the switching valve 38
is switched depending on the supply pressure, and either the lower chamber is supplied with oil to move the copying ram backward, or the upper and lower chambers are supplied with oil and the copying ram is moved forward by the differential pressure between the pressure receiving areas. The NC control device has a well-known configuration with a W axis in the traverse direction and a Y axis in the cutting direction, and the data input device 4
5. Data storage unit 46, comparison calculation units 47, 50 for the W axis and Y axis, respectively, directional and speed command units 48, 51, drive units 49, 52, feed motors 21, 9, tachogenerators 22, 10, detection It is configured to include containers 23 and 11.

Next, the operation of the present invention will be explained.

A. Normal dressing following template 29 in Figure 3.

The grindstone 1 has two plates 1a and 1b spaced apart from each other, and the template 29 has a two-step shape. Now, the copying saddle 18 is in a standby position on the left side of the W axis in the figure, the copying ram 27 is at the upper end position with hydraulic pressure being sent to the lower chamber of the cylinder 31 of the hydraulic copying device, and the cutting table 2 is on the upper side of the Y axis. It is in the standby position. In response to a dressing command from the NC, the diamond tool 28 is moved and positioned from point _P1 to point _P2 on the W axis by the rotation of the feed motor 21, which rotates the ball screw 17 at a rapid traverse speed of v _i . Next, the 2-position switching valve 36 is switched, and the 2-position switching valve 38 is switched as the oil passage is switched, so that pressure oil is simultaneously supplied to the upper and lower chambers, and the piston rod 3
The copying ram 27 is moved forward by the pressure caused by the difference in the pressure receiving area of the piston due to the feeler 3.
0 is brought into contact with the surface 29a of the template 29 with a constant pressure. Next, the Y-axis is controlled to rotate the motor 5 to advance the cutting table 2 and the diamond tool 28.
is positioned at a position for dressing the grindstone 1a. Next, control the W axis to reverse the feed screw 17 and move the copying saddle 18 and the diamond tool 28.
P Move and position up to ₃ points at dressing speed v ₁ . During this time, the diamond tool 28 rotates one slope of the grinding surface of the grindstone 1a to the surface 29a of the template 29.
Dress according to the instructions. Next, by controlling the W axis, the copying saddle 18 is moved and positioned at the dressing speed v ₂ ' to point P ₄ ' on the W axis. During this copying, the filler 30 slides and copies the stepped surface 29b of the template 29, so the diamond tool 28 dresses the left slope of the grindstone 1a and moves to point _P4 at a speed _v2 . The position of point _P4 ′ is the position obtained by subtracting the template step × tan30° from the position of point _P3 . Next, by controlling the W axis, the copying saddle 18 and the diamond tool 28 are moved and positioned at a slightly faster speed vj ₁ to the dressing start point _P5 of the grindstone 1b. During this time, the diamond tool 28 follows the template surface 29c. Next, the W axis is controlled in the same way, and the copying saddle 18 and the diamond tool 28 are
Move and position to point _P6 at dressing speed _v3 . The diamond tool 28 dresses the grinding surface of the grindstone 1b by following the surface 29c of the template 29. Next, when the W-axis is controlled and the copying saddle 18 is moved to point P ₃ ' at a dressing speed v ₄ ', the diamond tool 28 of the copying ram 27 follows the slope 29d of the step of the template 29 to point P ₇
Move to point with velocity v ₄ , then template 29
It moves along the surface 29e at a scanning speed v ₄ ' and is positioned at point _P8 . During this time, the diamond tool 28 dresses the left slope of the grindstone 1b. Next, the two-position switching valve 36 is switched to change the direction of the pressure oil in the cylinder 31 and the piston 32 is moved backward, thereby moving the copying ram 27 backward and returning to the standby _P1 point to complete one cycle. Next, control the Y axis with NC to adjust the cutting head little by little, e.g. 0.01 to 0.03 mm.
The dressing is advanced and the next dressing is performed, and the cycle is repeated several times to complete the dressing. During this cycle, the speeds during coarse dressing v ₁ , v ₂ ,
Finish dressing speed v ₂₁ for v ₃ , v ₄ ,
It is possible to freely set the speed according to the grinding wheel position and the number of corrections using NC control, such as slowing down v ₂₂ , v ₂₃ , and v ₂₄ .

B Applied operation of step correction of the template shown in Fig. 4.

This is used as a countermeasure when it is not possible to process according to the shape of the template 29 due to the wear status of the grindstone, processing conditions, etc., or when dressing cannot be performed according to the template due to machine characteristics even if the same template is used, or when you want to slightly change the height difference of the grindstone. be done. The diameter of the large diameter part of the stepped workpiece is now D ₂ 〓△
D ₂ = When it is desired to process a large pattern, the basic dressing cycle is the same as in case A, so the different parts will be explained. When the diamond tool 28 is at point _P4 , if the cutting table 2 is cut by △D ₂ /2sec30° at a speed much faster than the dressing speed using Y-axis control, the feeler 30
The diamond tool 28 is advanced by △D ₂ /2sec30° while following the template surface 29c,
The actual tracing surface is moved forward by ΔD ₂ /2 from the template surface 29c, so the diameter of the grinding wheel can be reduced accordingly and the diameter of the workpiece can be increased by ΔD ₂ /2.

C Applied motion of copying the reverse step shown in Fig. 5.

If the shape of the template is upwardly sloped when being corrected in the whetstone correction device, it is difficult to correct the pattern using the hydraulic direct method.
When machining a workpiece with such a reverse level difference, the Y-axis positioning is changed at a position unrelated to the grindstone correction.

Simultaneous two-axis control of the W-axis and Y-axis, or one-axis control with the W-axis stopped. The grinding wheel 1 consists of two sheets 1a and 1b spaced apart, and the basic dressing cycle is the same as that of A. However, since the grinding wheel 1b has a larger diameter than the grinding wheel 1a, the feeler is not suitable for hydraulic machining in which the machining is carried out with a descending step. Difficult due to angle. Therefore, when the diamond tool 28 reaches the _P4 point, the Y-axis is moved in the + direction by a predetermined amount at a speed faster than the dressing speed from this position, which is unrelated to the grinding wheel correction, in other words, the cutting table is retreated by a predetermined amount, and the cutting table is moved back simultaneously with the W-axis control.
Using axis control, the diamond tool ₂₈ is moved back to point _P5 ', which is before the dressing position of the grinding wheel 1b.
Send the W axis at a slightly faster speed to the point. Thereafter, by performing dressing in a regular cycle, it is possible to trace the reverse level difference. Of course, it is also possible to stop the W axis and control only the Y axis.

D An applied operation for undercutting the corners in Figures 6 and 7.

If the small diameter part of the workpiece of the stepped shaft fits into the hole in the machine base, and the corner of the stepped part has a recess so that the end face of the stepped part can accurately contact the machine base surface, the edge of the grinding surface of the whetstone will normally be There is a slight radius, and if left as is, there will be uncut parts at the base of the step.
An annular protruding grinding surface is provided at the edge of the grinding surface of the grinding wheel so that there is no uncut material, and the template 29 of the correction device has a convex portion extending from the sloped portion to the R portion so as to lengthen the straight portion of the grinding wheel surface that grinds the side surface. 29
f is formed. However, if a deep clearance is required, this angle of inclination becomes large and the structure of the correction device makes it impossible for the filler to follow the surface. In such a case, when the filler 30 is moving uphill between points _P10 and _P11 on the template, the corrected end face straight line amount H is H=Yi+h, where Yi=step difference correction amount h=end face straight line amount of the template. The W axis is stopped and the Y axis is controlled so that the cutting table 2 is moved back by an amount Yi to make the end face straight line length longer to a desired value. The amount of change L ₁ minute in the longitudinal dimension of the template due to this correction is subtracted when the template is manufactured. The same cycle as in case A is repeated to correct the parts other than this convex part. In this case, it is necessary to manufacture the template in consideration of the fact that the correction position, correction amount, and correction shape will differ depending on whether the R of the filler tip and the radius of the diamond tool tip are the same or different.

Furthermore, although the present embodiment has been described with respect to the grindstone correction of an angle slide grinder, it can also be applied to other grinders such as a cylindrical grinder without major changes. Furthermore, it is of course possible to combine it with other copying devices such as electric copying instead of hydraulic copying.

As described in detail above, the present invention not only uses hydraulic pressure, etc., but also uses the W-axis in the traverse direction and the Y-axis in the cutting direction.
Since the correction operation is performed in combination with NC control, it is possible to correct the template when the correction accuracy is not correct depending on the machine, by making the template appear to be corrected by the Y-axis NC control. This eliminates the need for difficult and expensive template modifications, and also allows you to add or delete columns precisely in different positions than the template, eliminating the need to create individual templates. It can reduce production costs. In addition, as in the case where the second wheel of a two-wheel grindstone has a large diameter, the rising angle is relatively steep and corrections that cannot be made by just copying can be made, making it possible to handle a wide range of work. Furthermore, since dressing of points such as tapers and crowning parts is done by conventional profiling, a smooth surface finish can be obtained. Furthermore, the correction speed can be easily varied depending on the dressing position, making it extremely easy to set the depth of cut and other conditions.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a part of the correction device using the present invention for an angle slide grindstone, Fig. 2 is a schematic configuration diagram of the NC device, and Fig. 3 is the movement of the diamond tool during normal dressing. Figure 4 is an explanatory diagram of template level difference correction, Figure 5 is an explanatory diagram of copying the reverse level difference, Figure 6 is an explanatory diagram of the machining state of corner hollowing, and Figure 7 is an enlargement of the inside of the circle in Figure 6. It is an explanatory diagram. 1... Grindstone, 2... Cutting stand, 3, 17... Feed screw, 5, 21... Feed motor, 15... Traverse table, 18... Copying saddle, 27... Copying ram, 28... Diamond Tool, 29...template, 30...feeler, 31...hydraulic cylinder.

Claims (1)

[Scope of Claims] 1. In the grinding wheel correction of a grinding machine, the feeding of the grinding surface of the grinding wheel such as the taper part or the crowning part of the workpiece is performed by template tracing using fluid pressure or electrical control, and the feeding of the grinding wheel grinding surface of the workpiece is performed by template tracing by fluid pressure or electrical control, and the tracing correction member is moved in the grinding wheel generatrix direction. A copying and NC method characterized in that traverse feed is performed under NC control, and cutting or returning of the correction member at a stepped portion or straight portion of the grindstone, or cutting or returning to correct a shape different from the shape of the template is performed using NC control. How to repair a grinding wheel. 2. In a grinding wheel correction device for a grinding machine, a copying tool is provided with a diamond tool at the tip for correcting the grinding surface of the grinding wheel, a feeler at the rear end for contacting a template for copying, and is supported movably in the cutting direction of the grinding wheel. A ram, a fluid pressure or electric driving means for causing a feeler of the copying ram to follow a template, a copying saddle on which the copying ram and the driving means are placed and supported so as to be movable in a grinding wheel generatrix direction, and the copying saddle an NC drive control means for traversing the copying saddle, a traverse table supporting the copying saddle, a cutting table provided on the grinding wheel table on which the template is placed and movable in the cutting direction of the grinding wheel; A grinding wheel correction device using copying and NC, characterized in that it is equipped with an NC drive means for giving cutting and return feed, and performs dressing by copying and NC control.